Telephone-exchange system



March 2 1926. 1,575,336

J. H. HENRY TELEPHONE EXCHANGE SYSTEM Filed Oct. 16, 1924 15 Sheets-Sheet 1 March 2 1926; 1,575,336

I. H. HENRY TELEPHONE EXCHANGE SYSTEM Filed Oct. 16, 1924 15 Sheets-Shet 2 by W $72 March 2 1926. 1,575,336

. I. H. HENRY TELEPHONE sxcrmues SYSTEM Filed Oct. 16, 1924 15 gr ets-sheet 5 March 2 1926.

I; H. HENRY TELEPHONE Exxmxcs SYSTEM Filed Oct. 16, 1924 13 Sheets-Sheet- 4 March 2 1926. 1,575,336

l. H. HENRY TELEPHONE EXCHANGE SYSTEM Filed t. e 1924 March 2 1926.

I. H. HENRY TELEPHOEE' mgwhusm SYSTEM 15 Sheets-Sheet 6 Y March 2,1926. 1,575,336

I. H. HENRY TELEPHONE EXCHANGE SYSTEM Filed Oct. 16 1924 l5 Sheets-Sheet '7 I. H, HENRY TELEPHONE EXCHANGE; SYSTEM March 2 1926.

13 Sheets-$11661; 8

March 2', 1926.

l. H. HENRY TELEPHONE EXCHANGE SYSTEM Filed Oct. 16, 1924 15 SheetsSheet 9 March 2 1926.

I. H HENRY TELEPHONE EXCHANGE SYSTEM Filed Oct. 16, 1924 13 Sheets-Sheet 10 March 2 1926. I. H. HENRY .TELEPHONE nxcrmnss SYSTEM Filed get. 16, 1924 ls'sheetsf-sheet 11 March 2 1926.

l. H. H ENRY TELEPHONE EXCHANGE SYSTEM Filed 00 t. 16, 1924 15 Sheets-Shet' 12 March 2 1926.

l. H. HENRY TELEPHONE EXCHANGE SYSTEM Filed Oct. 16, 1924 13 Sheets-Sheetw [ill Patented Mar. 2, 1926.

UNITED. STATES 1,575,336 PATENT OFFICE.

ISRAEL H. HENRY, or EAST oEA eE; NEW anesnmassrenon 'lO WESTERN ELEC- TRIO COMPANY, INCORPORATED, on NEW YoEx, N. Y., A, coEroEATToN on NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed October- 16, 1924. Serial. No. 743,920.

To all 107mm 2'] rim/1y concern: i

Be it known that I, IsRAEI. H. HENRY, a citizen of the United States of America, residing at East Orange, inthe county of Essex and State of New Jersey, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems and more particularly to systems in which automatic switches are employed in the establishment of connections.

In automatic telephone systems where connections are cstablishedunder the control of register senders, these senders. are associated with all calling subscribers lines during. the establishment of a connection. In the case of certain lines it is necessary that a coin be deposited by the subscriber before a col'nplete connectioncan be established. In the case of these lines it has been customary to associate a register. sender with the line a second timein order to collect or refund this coin. Since a register sender is a complex and expensive organization it is desirable to reduce the time during which it is employed in connection with each, call, in order that the total numbernecessary to serve an exchange maybe reduced to the least number consistent'with good service.

It is an object of the present invention to provide means for collecting and refunding a coin deposited at a subscribers substation independent of the register sender.

A feature of the invention lies in the provision of a plurality of mechanisms any one of which may serve to'collect or refund the coin deposited in connection with. a particular call.

Another feature of the invention lies in causing all idle coin control mechanisms to hunt for an extended line at the substantion of which a coin is to be collected or refunded.

Gther features of the invention will be evident from a consideration of the following description inconnection with the draw lugs and appended claims.

In the drawings, Fig. 1 shows one of a group of subscribers lines, together with the trip circuit serving. the group.

Fig. 2 shows a start circuit. serving a plurality of groups of lines.

Fig. shows a line finder-district selector circuit for extending the line.

Fig. 4 shows one of the plurality of link circuits serving the subgroup including the line 100.

Figs. 5, 6, 7 8, 9, 10 and 12show the circuits of the register sender adapted to be selected by the link circuit ofFig. 4 and to control the switches in their selective action.

Fig 11 shows a diagrammatic form switches necessary to extend theconnection from the district selector of Fig. 3.

Fig. 13 shows one of a plurality of coin control circuits embodying in. part the present invention.

Fig. 14- is a diagram showing the manner in which the several'figures of the drawing should be arranged to show the complete circuits of the invention.

Before proceeding with the detailed description a brief statement of the operation of the circuits may be desirable.

Subscribers lines such as line 100 are connected to multiple terminals appearing before a plurality of line finders. These multiple terminals are arranged in a plurality of groups each group beingv served by a separate brush set on each finder and each group being divided into two subgroups. A trip circuit is provided individual to each group; a start circuit is provided for all the groupsof lines served by the group ofline finders; and a plurality of link circuits are provided for each group of lines and line finders. The line finders and link circuits are divided into two subgroups and each such subgroup normally serves calls in the corresponding subgroup of lines. The arrangement is such that, except when all link circuits are busy, a particular'link circuit will be in readiness to serve a call and will be connected by its district finder to an idle line finder.

When a call is initiated by a subscriber in a particular group, the trip circuit individual to the group, and the start circuit are taken for use by that line and means are provided for preventing the extension of a call in the other subgroup of the group or in any other group until the line finder has been started in search of this calling line. Means are also provided for preventing the extension of a second call in this group unle'ft contact of relay 103 to ground.

til after simultaneous calls in other groups have been taken care of. The operation of the start circuit causes the line finder associatedvwith the link circuit allotted for use, tohunt for the calling line and also causes the linkcircuit to hunt for an idle sender. As soon as a particular link is taken for use With a call the next link is allotted to'serve the next incoming call in the particular subgroups Which they serve. As soon as a brush set'on the line finder has been tripped the start circuit will be freed to permit the extension of calls in other groups. As soon as the line has been found the trip circuit of the group is freed by the line finder to extend another call in the same group provided no call is awaiting extension in another group. As soon as selectionsare completed the sender and link circuit are released by the district selector circuit and the link circuit immedi ately hunts for another idle district- Substation 100 is one at which a coin box is located for the purpose of requiring prepayment for calls. Substations of this type are served by register senders which are arranged to prevent the completion of a connection unless the required-coin is'deposited in said coin box. I V j t hen the subscriber at substation 100 removes his receiver from the switchhook a circuit is closed for line'relay 101 extending from battery through that relay, inner contact of relay 102 over the subscribers' loop to ground at the outer contact of relay 102. Relay 101 operates and closes a circuit from battery, resistance 104, through the winding of relay 103 to ground at the outer contact of relay 101.

The operation of relay 1.03 closes a circuit from battery, resistance 105 to ground at the outer right contact of relay 103. This circuit is in shunt of the winding of relay 106, which relay serves the second subgroup of the group to which line 100 belongs, thus preventing the extension of a call from that subgroup, while the trip circuit is in use with line 100. The operation of relay 103 also closes a circuit from battery, through the winding of relay 200,. conductor 133, outer left contact of relay 107, outermost In addition relay 103 closes a circuit from ba ttery, over the back contact of relay 201, right winding of trip relay 108, inner left contact of relay 107, innermost left contact of relay 103, left contact of relay 109 to ground.

Relay 10 8 operates in this circuit and closes a locking circuit for itself from ground, right contact of relay 109, left winding and inner left contact of relay 108 over the inner left back contact of the trip relays of the other groups of lines, conductor 129, right winding of start relay 201 to battery. Relay 201 operates in this circuit.

A circuit is now closed for relay 110 extending from battery through the winding of relay 110, right contact of relay 108, conductor 128, to ground at the outer right contact of relay 201. Relay 110 locks in an obvious circuit to ground at the left back contact of relay 109. Relay 108, together with relay 103 closes a circuit from the outer contact of relay 110, outer left front contact of relay 108, inner right contact of relay 103, conductor 131, left back contact of relay 202, outer left back contact of relay 203, conductor 206, upper contact of cam 401, upper contact of cam 402, brush 461 and its associated terminal, conductor 378, lower left and upper right contacts of cam 301, winding of relay 302, to battery, the line finder of Fig. 3 having been assumed to have beenallotted for use by the switch 460 and the sequence switch 300 therefore standing in position 2.

The operation of relay 108 also closes a circuit from ground over its outer right contact, through the winding' of the trip magnet 303, serving the group in which line 100 appears on the line finder frame, to battery. Relay 110 upon operating closes a circuit frombattery, through the left winding of relay 109, left winding of relay 107, outer contact of relay 110 to ground. Helay 107 operatesand locks through its right winding and inner right contact to the contact of relay 200.

The operation of relay 302 closes a circuit from battery, through the winding of updrive magnet 304, inner left contact of relay 302, upper left contact of cam. 364, left front contact of relay 302 to ground.

Under the control of the updrive magnet 304 the line finder shaft is moved upwards. Due to the operation of the trip magnet 303 the set of brushes serving the group of lines to which line 100 belongs is tripped. When the magnet leaves the tripping Zone a circuit is closed from ground over brush 307. through commutator segment 305, upper contacts of cam 306, outer left normal contact of key 204, inner right contact and right winding of relay 201 to battery. Relay 201 is held operated in this circuit but the circuit through the locking winding of relay 108 is shunted and that relay releases, in turn releasing the trip magnet 303. As soon as brush 307 leaves segment 305 the circuit of relay 201 is opened and that relay releases again connecting battery to the operating windings of relay 108 and the corresponding relays in other trip circuits, so that subsequent calls may be served.

Relay 302 closes a locking circuit for itself over its inner right contact, lower left contact of cam 308, back contact of relay 320, commutator segment 321, brush 322, to

ground, which is closed as soon as the line finder shaft moves upward. Relay 302 also closes a. circuit from battery, over the inner left contact of relay 205, right winding of relay 203, conductor 207, left contacts of cam 403, brush 462, and its associated terminal, conductor 37 9, lower rightcontact of cam 311, outer left front contact of relay 302 to ground. The operation of relay 203 removes ground from conductor 206 thus preventing the start of another line finder until the brushes are tripped. Relay 203 locks in a circuit from battery, over the outer left contact of relay 205, left winding aud outer left front contact of relay 203, left back contact of relay 202, conductor 131, inner right contact'of relay 103, outer left contact of relay 108, outer contact of relay 110 to ground. The operation of relay 203 also closes a locking circuit for relay 201 from battery, left contact and left winding of relay 201, inner right contact of .relay 208 to ground. The circuits just traced are established before relay 108 is rel-eased by the shunting action of co1nmutato r segment 305. As soon however as relay 108 deenergizes it opens the locking circuit of relay 203, restoring the start circuit to condition to serve subsequent calls.

lVhen relay 302 operates it also closes a circuit from ground through its-outer left front contact, lower right contact of cam 311, conductor 379, brush 462, and its associated terminal, right contact of cam 404., upper left contact of cam. 405, right winding of relay 406, winding of relay 407, upper left contact of cam 408, upper right contact of cam 409, resistance 410 to battery. Relays 406' and 407 operate, relay 406 closing a'locking circuit for itself and relay 407 from battery, through resistance 410, upper right contact of cam 409, upper left contact of cam 408, winding of relay 407 ,1 right winding of relay 406, contact of cam411, contact of relay 406 to ground. Relay 407 closes acircuit from battery, through the winding of sequence switch magnet 400,

upper contact of cam 412, contact of relay 407 to ground. Magnet 400 operates adyancing the link circuit sequence switch to position 2.

In position 2 ground is connected from the right contact of cam 415 to brush 466 and its associated contact, conductor 375, lower left contact of cam 312, lower right contact of cam 318, right winding of relay 314 to battery. Relay 314 operates, but performs no function until the calling line has been found. Ground from the front contact of relay 406 is also extended over the contact of cam 411, upper left contact of cam 405, upper right contact of cam 404, left contacts of cam 403, conductor 207, right winding of relay 203, inner left contact of relay 205 to battery, holding relay 203 operated. until the link circuit is moved out of position 1. When the link circuit arrives in position 2 relays 406 and 407 release. .The release of relay 407 completes a circuit from ground at the back contact of relay 407, upper right and lower left contact of cam 405, winding of magnet 487 to battery. Magnet 487 op crates and closes an. obvious circuit for magnet 488. Magnet 488 is the rotary mag net for sender sector switch 480 and causes the switch to rotate. in search of an idle sender.

An idle sender is characterized by the c0nnection of battery, through a 150 ohm re sistance, such as resistance 501, to conductor 502 and its corresponding terminal in the set engaged by brush 483. With the link circuit sequence switch in position 2 ground is connected over the upper right contact of cam 421, through the left winding of relay 406, lower contact of cam 413, right winding of relay 406, winding of relay 407, lower contact of cam 401, lower right contact of cam 402 to brush 483.

When brush 483 encounters a terminal corresponding to an idle sender, to which battery is connected, relay 406 operates,

short circuiting its left hand winding over its contact and the contact of cam 411, per-.

initting relay 407 to operate in series with the right hand winding of relay 406. The operation of relay 407 opens the circuit of magnet 487 and closes a circuit from battery through the winding of sequence swiitclr magnet 400, upper contact of cam 412, front contact of relay 407 to ground advancing the link sequence switch to position 3.

In position 3 a circuit is prepared extending from ground through the right and middle windings of relay 503, inner left con-r tact of relay 504, right back contact of relay 505, conductor 506, brush 484 of sender selector 480, lower left and upper right contacts of cam 408, brush 464 of district finder 460 to conductor 315, left contact of cam 316, right Winding of relay 817 to battery,

which circuit is not "completed until the,

district circuit reaches position In the meantime the line tinder shaft continues to move upwards until it reaches the terminals corresponding to the calling subscribers line; hen these terminals are encountered a circuit is completed from battery, through the right winding of relay 109 and resistance 111 in parallel, inner front contact of line relay 101, conductor 114, terminal 880, brush 88 1, upper left and lower right contacts of cam 318, winding of relay 320 to ground. Relay 320 operates and closes a circuit in shunt of its winding through resistance 319, right front contact of relay 320, commutator segment 321, brush 322 to ground. Relay 100, which is marginal, isso adjusted as not to operate in the circuit previously traced in series with relay '107 or in the circuit traced for the winding of relay 3,20. Withresistance 319 in parallel with relay 320 relay 109 operates and locks through its left hand winding, left winding of relay 107, outer left contact of relay 110 to ground. The operation of relay 109 opens the locking circuit of relay 110 and relay 110 releases after an interval due to the fact that it is slow to release. Relay 320 opens the locking circuit of relay 302 and that relay releases as soon as brush 310 encounters, an. insulating segment of centering cam 309.

The release of relay-302 opens the circuit of updrive magnet 304 and stops theline finder on the calling subscribers line. it also connects battery through resistance 323 and its outer right back contact, upper contacts of cam 324, inner back contact of relay 387, resistance 325, brush326, andterminal 327, over conductor 112, winding of cut-off relay 102 to ground. Relay 102 operates and releases line relay 101 removing the calling condition from terminal 380 and opening the circuit of relay 109 which releases. The release of relay 101 permits relay 103 to release and also opens the circuit of relay 320. The connection of battery with termi- .nal 327 marks terminal 113 and the other multiple terminals of calling line 100 in the terminal banks of final selectors with reducedbattery potential to render theline busy at such final selectors. The release of relay 302 also closes a circuit from battery through the winding of sequence switch magnet 300, upper left contact of cam 328, left front contact of relay 314, left back contact of relay 302 to ground. Se quence switch 300 is advanced in this circuit to position 3.

Vhen sequence switch 300 leaves position 2 the circuit of relay 31$ is opened and that relay releases. When the sequence switch 300 reaches position 3, the previously traced circuit for relays 503 and 317 is completed. Relay 317, being marginal does not operate at this time. Relay 503 operates and closes an obvious circuit for relay 507 which in turn closes a circuit from battery, through resistance 508, winding of'relay 509, outer left front contact of relay 507 to ground; Relay 509 operates and looks over its inner right front contact. Relay 507 closes a circuit for relay 510 from battery, winding of relay 510, conductor 534, to ground, at the inner left front contact of relay 507. It also closes a circuit from battery, through the winding and right normal contact of relay 601, normal contact of brush 602 of timing switch 600 and thence to ground over conductor 534to the inner right front contact of relay 507. The operation of relay 510 closes an obvious circuit for relay 511 which in turn closes a circuit through the left winding of relay 512. The operation of relay 601 closes a circuit from battery,

through the winding of relay 603, normal terminal and brush 60 1 of switch '600, inner The operation of relay 512 opens the circuit .previously traced from battery, through resistance 501, to relays'al00 and 4-07 and these relays release. The release of relay 4107 closes a. circuit from battery, through the winding of sequence switch magnet 400, lowerright contact of cam 112, back contact of relay 407 to ground. Sequence switch 400 is advanced to position 4: from which position it is moved to position 5 by means of ground over the lower left contact of cam 112.

In position 5 of the link sequence switch 100 the dialing leads and the fundamental circuit leads are cut through directly from the district circuit to the sender circuit; The

dialing circuit may be traced from battery,

through the left winding of relay 000, conductor 637, left back contact of relay 1200,

left back contact of relay 1201, conductor 1202, sender selector brush 135, and its correspondingterminal, lower contacts of cam 114, district finder brush 465 and its corresponding terminal, conductor 382, lower left contact of cam 329, winding of relay terminal, conductor 1203, right back contact of relay 1201, right back contact of relay 1200 to ground.

I In position 5 of the link circuitsequence switch 100, relays 4106 and 407 are connected in a circuit extending from brush 184, left contacts of cam 40S, wind-ing of relay 407, right winding of relay 406, vupper contact of cam 4:13, to brush 16-1. The circuit of these relays is extended from these brushes as will be later described. \Vhen the dialing circuit above traced is completed, relay 606 operates and closes a circuit from battery, through the winding of relay 610, front contact of relay 600, conductor 639, inner right back contact of relay 515 to ground. Relay 610 operates and closes a circuit from battery, through the winding of relay 609, right front contact of relay 610, conductor (338, upper left contact of cam 516 to ground. As soon as relay 009 operates the dialing tone circuit is completed as follows: From source of tone 607, right winding of relay 000, normal terminal and brush 1 of register steering switch 800, (mtermost left contact of relay 609, conductor 618, lower contact of cam 514, conductor 534, to ground at the inner left front contact of relay 507.

Due to the closure of this circuit a tone is induced in the left winding of relay 606 and over the dialing circuit to the receiver of the subscribers telephone to indicate that dialing may be started. The subscriber now dials the number of the wanted subscriber.

Dialing takes place, and the registers 310, S20, 1000, 1010, 1020, 1030 and 1040 are positioned. as described in the copending application of O. H. Kopp, Serial No. 743,919 filed Oct. 16, 1924. As soon as registers 810 and 820 are set, translator 830 is positioned to control various selections, after which class sequence switch 950 is positioned. As soon as the translator positioned sequence switch 500 is z-ulvanced to position 2.

With the sequence switch 500 in position 2 the fundamental circuit is completed from battery, through the right winding of re lay 3H, lower right contact of cam 313, lower contact of cam 312, conductor 373, brush l61 and its associated terminal, upper right and lower left contact of cam e02, brush 4-81 and its associated terminal, right back contact of relay 504, right contact of cam 701, winding of stepping relay 702, back contact of relay 703, left winding of relay 704, left contact of cam 705, inner right contact of relay 620, middle left contact of relay 621, resistance 023to ground, relays 620 and 621 having energized'upon the setting of'the translator switch 830 in the manner set forth in the aforementioned application of O. H. Kopp. Relays 314iand 702 operate in this circuit but relay 70a is polarized and does not. Relay 314 looks through its outer right front contact, lower left contact of cam 313, lower right contact of cam 312, to the fundamental circuit as previously traced. Relay 314:. in operating also closes a circuit from battery through the winding of sequence switch magnet 300, upper left contact of cam 328, left front contact of relay 31 1, left back contact of relay 302 to ground. Magnet 300 energizes in this circuit and advances the sequence switch to position 4.

In position l the energizing circuit for relay 314 is opened but the locking circuit is maintained closed. At the same, time a parallel circuit is prepared from the outer right front contact of relay 314, lower left contact of cam 313, upper right contact of cam 312, commutator segment 337, brush 33S, upper left contact of cam 339 to ground.

In position 4 relay 314 closes a circuit from battery, through the winding of updrive magnet. 340, upper right contact of cam 341, left front contact of relay 314;, back contact of relay 302 to ground. The updrive mags net energizes in this circuit andcauses the district selector switch shaft to move up ward in a brush selecting movement. a Each time that brush 338 makes contact with a conducting segment of; strip 337 the parallel. circuit above traced is completed, in which circuit relay 314i is held operated and the stepping relay of the sender shunted.

When the fundamental circuit above traced was closed and stepping relay 702 operated, it closed a circuit from battery, inner left contact of relay 021, left contact of cam '519, winding of the No. 3 counting relay, (assuming that the translator has been set in position to select the fourth. brush on the district selector) back contact of the No. 3 counting relay, conductor 706, translator brush 855 and its corresponding terminal, right contacts of cam 707, inner left back contact of relay 703, left contact of cam 520, contact of relay 702, lower left contact of cam 518 to ground. The No. 3 counting relay operates in this circuit and looks through the winding of the No. 3 counting relay, front contact of the No. counting relay, upper right contact of can1709 to ground. The No. 3 counting relay does not operate at this time sinceits winding isshunted by the energizing circuit of the No. 3count1 ng relay. When, in its upward movement, brush 338 of the district selector encounters the first conducting segment of commutator strip337, stepping relay 702 is shunted and deenergized, opening the above traced circuit for the N o. 3 counting relay permitting the No. 3 counting relay to operate in the locking circuit of the No. 3 counting relay.

The energization of the No. 3 counting relay connects conductor 706 through the back contact of the N0. 2 counting relay, to the winding of the No.2 counting relay and thence. to battery. 'lVhen brush 331 on counters an insulating segment the shuntis removed from relay 702 and that relay again energizes closing the circuit from ground to conductor 7 06 causing the energization of the No. 2 counting relay. As the district selector switch shaft continuesupward and brush 338 engages the insulating and conducting portions of the commutator strip 337, stepping relay 702 is alternately deenergized and energized and the counting relays successively operated. When brush 338 reaches the fourth conducting segment and stepping relay 702 deenergizes for the fourth time, the 0 counting relay operates in parallel with relay 703 and in series with the No. 0 counting relay. The operation of relay 703 opens the fundamental circuit and permits the release of relay 314 as soon as brush 338 leaves the conducting segment. The operation of the 0 counting relay closes a circuit from battery through the winding of sequence switch magnet 700, right contact of cam 710, left back contact of relay 708, front contact of the "0' counting relay to ground at the inner back contact of relay 711. Sequence switch 700 is energized in this circuit and advances the sender sequence s itch to position 3. As soon as sequence switch 700 leaves position 1% the locking circuits of all operated counting relays are opened, releasing such relays. The release of relay 314 as previously described opens the circuit of up-drive magnet 340 and closes a circuit from battery, through the winding of sequence switch magnet 300, right contacts of cam 342, outer left back contact of relay 314, back contact of relay 302 to ground, in which circuit the sequence switch is advanced to position 5.

lVith sequence switch 300 in position 5 and sequence switch 700 in position 3 the fundamental circuit is again closed from battery, through the right winding of relay 314, lower right contact of cam 313, lower right contact of cam 312, conductor 378, thence as traced previously, outer right back contact of relay 504, right contact of cam 701, winding of relay 702, contact of relay 703, left winding of relay 704, left contact of cam 705, innermost right contact of relay 620, middle left contact. of relay 621, resistance 623 to ground. Relays 314 and 702 operate in this circuit as before. Relay 314 locks as previously described and closes the previously traced circuit for sequence switch 300 in which circuit the se quence switch advances to position 6. The operation of stepping relay 702 closes a circuit from battery, right contact of cam 519, through the winding of the No. -1 counting relay (assuming that the trans lator is set in position to cause the selection of the second group of outgoing trunks served by the fourth set of brushes) back contact of the No. 1 counting relay, conductor 712, translator brush 854, lower right and upper left contact of cam 707, inner right back contact of relay 708, left contact of cam520, contact of relay 702, lower left contact of cam 518 to ground. In positions 5 to 7, inclusive, of sequence switch 300 trip magnet 343 is energized in a circuit extending from battery through its winding, to ground at the lower right contact of cam 336. hen the sequence switch arrives in position 6 updrive magnet 340 is again energized and the district selector switch shaft is moved upward in a group selecting movement. Due to the energization of trip magnet 343 and the positioning of the district selector in accordance with the brush. selecting operation just described left contact of cam 313 to the fundamental circuit as previously traced. As the district selector moves upward the stepping relay 702 will be periodically shunted and the counting relays operated beginning with the No. 1 counting relay. \Vhen the 0 counting relay operates at the second re lease of relay 702, relay 703 is operated releasing relay 314 and bringing the district selector to rest with its brushes engaging the first terminal of the second group-to which the fourth brush set has access.

The release of relay 314 also closes a circuit from battery through the winding of sequence switch magnet 300, right contacts of cam 342, outer left back contact of relay 314to ground at the back contact of relay 302 advancing the sequence switch to position 7.

In position 7 of sequence switch 300, relay 314 is operated in a circuit from battery through its left winding, left contacts of cam 347, contacts of cam 308 back contact of relay 320, line finder commutator segment 321, brush 322 to ground. The operation of relay 314 closes a circuit from battery, through the winding of sequence switch magnet 300, upper left contact of cani left front contact of relay 314, back contact of relay 302 to ground. Sequence switch 300 is advanced in this circuit to position 3.

In position 7 to 8 relay 314 looks over its inner right front contact, lower contacts of cam 348, to the sleeve brush 349 and ground over the sleeve terminal of the trunk, provided that trunk is busy. The energizing circuit of relay 314 is opened in position 8. If the first trunk of the group is busy and relay 314 is held energized in position 8, a circuit is completed for the updrive magnet 340 frombattery,through the winding of the magnet 340, upper right contact of calm 341, left front contact of relay 314 to ground at the back contact of relay 302. The updrive magnet is energized and causes the district selector shaft to move upward in searchof an idle outgoing trunk. Relay 314 is held operated between terminals over a circuit extending from battery, through its left winding, up per contacts of cam 347, commutator segment 384, brush 371, lower left contact of cam 341, outer left front contact of relay 314, back contact of relay 302 to ground. As soon as an idle trunk is reached, characterized by the absence of ground on its sleeve terminal, the locking circuit of relay 314 is opened and the relay releases in turn ing" of sequence switch magnet 300, right contacts of care 3 t2, left back contact of relay 314-, back contact of relay 302 to ground, advain-3.1m, the sequence switch to position 0.

As soon as relay 314- releases, ground is connected to sleeve terminal 383, over the upper right contact of cam 330, outer right back contact of relay 314, right contacts of cam 350, through. sleeve brush 3 19, to render the selected trunk busy. As soon as the sequence switch arrives in position 8% ground is connected overthe lower left and upper right contacts of 011111350 and sleeve brush 3410, to sleeve terminal. 383, independent of relay 314-, which ground is maintained until the sequence switch leaves, position 15 lVith sequence switch 300 in position 9 a circuit is completed from battery through the winding of relay 351 upper leftcontact of cam 316, conductor 315, to brush 4-61 and its associated terminal, and thence tljirough the right winding of relay 4106, and the winding of relay 407, tobrush 48% and its associated contact as previously traced. From brush 184: this circuit is extended over conductor 506, right back contact of relay 505, inner left contact of relay 504, middle and right windings of relay 503 to ground. A parallel circuit is also closed through the right winding of relay 317, left contactsof cam 316 and thence as traced for relay 351 to ground. Relay 351 operates in this circuit, but relay 317 being marginal does not. The operation of relay 351 closes a circuit from battery, through the left winding of relay 31 1, upper right and lower left contacts of cam 352, left contact of relay 351, line finder commutator segmentbrush 35a to ground. Relay314- operates and closes a circuit from battery, through the winding of sequence switch magnet 300, upper left contact of cam 328,"left front contact of relay 314, left back contact of relay 302 to ground. Sequence switch 300 is advanced in this circuit to position 10in which position it remains during subsequent selections. y i

These subsequent selections take place, as described in the above identified application of O. H. Kopp with the exception of the manner of insuring that a coin has been deposited at the calling subscribers substation before permitting the completion of a connection.

T he operation of relay 507 at the time the sender is selectedfcloses a circuit from battery, through the winding of relay 601, right conductor 53st, inner left front contact of relay 507 to ground. Relay 601 in operating closes a circuit from battery, through the winding of relay 603, brush 601 and its normal terminal, inner left front contact of relay 601 to ground. Relay 603 closes a circuit from battery, through the winding of stenin i'na 'net 605 back contact of magnet 605, inner right front contact of relay (S03, brush 60st and its normal terminal, inner left front contact of relay 601 to ground. Magnet 605 operates and steps switch 600 to its first oft normal position.

Viith the brushes of switch 600 engaging their first oft normal terminals a circuit is completed from. battery, through the wind ing; of relay 1205, No. 1 terminal of brush 602, conductor 534 to ground. Relay 1205 operates and locks over its right front contact, outer right contact of relay1207, outer left back contact of relay 526, inner left back contact of relay 539 to ground over conductor 531-.

The operation of relay 1205 closes a circuit from lmttery, through the winding of relay 603,"ln-ush 601, and its No. 1 terminal, left front contact of relay 1205 to ground over coi'iductor 53st. Relay 603 operates and ca'usesthe operation of magnet 605 to ad vance switch 600 to its No. 2 position. The

steppingmagnet 605 is then energized over directed to the sender monitor operators position in the manner described in the above identified application of O. H. Kopp.

If dialinghas commenced and steering switch 800 has been advancedto its No. 1 position when switch. 600 steps to its No. position a circuit is closed from battery through the winding of relay 603, brush 631 and its No. 41- terminal, oft normal terminals of brush 805 to ground. Relay 603 operates and causes the operation of step ping magnet 605, advancing switch 600 immediately to its No. 5 position. advances to its No. 7 position under the con trol of interrupter 628.

If switch 800 has not been advanced to its No. 8 or No. 9 position at this time, a

circuit is closed from battery through lamp 632, resistance 633, No. 7 terminal and brush 62S), outer right back contact of relay 603, to ground at the back contact of relay 1201, and switch 600 remains in this position. However, if switch 800 is in its No. 8, 9 or, 10'position a circuit is closed from battery,

Switch 600' 

